Fossil Vertebrates from the Bahamas Introduction to the Paleontology of Bahaman Vertebrates Storrs L. Olson and Gregory K. Pregill In relation to their accessibility and their bio¬ still poorly known. What we hope to provide is logical interest, the Bahamas have been relatively an updated baseline, a consolidated starting poorly studied. The present collection of papers point, from which our knowledge can be ex¬ attempts to bring together all that is as yet known panded by future exploration. We would like to of one aspect of the natural history of the archi¬ think that we have shown that the little details of pelago, namely, vertebrate paleontology. This is anatomy, systematics, geology, and distribution largely an outgrowth of the more extensive and that are the building blocks of studies such as detailed collection of fossils obtained by Smith¬ those included here, eventually lead to significant sonian personnel in 1978 from the only truly generalizations of wider application. We will have productive vertebrate fossil locality yet discovered succeeded if this volume stimulates additional in the Bahamas—a sinkhole on the island of New research of this nature. Providence. In addition to analyzing this collec¬ The Bahamas form an extensive archipelago of tion, we have reviewed the literature on Bahaman low (maximum elevation 67 m), limestone islands fossil vertebrates and, with the exception of mam¬ and cays that are spread out over a distance of mals, we have re-examined and re-evaluated all nearly 1000 km. The larger islands are almost all of the previously reported fossil specimens. Par¬ in the northern part of the archipelago, where the ticularly in the case of birds, this has resulted in predominant vegetation type is pine forest (Pinus a number of taxonomic and nomenclatural caribaea ). Rainfall (data from Buden, 1979; Young changes. Furthermore, we have attempted to in¬ and Cant, 1977) is greatest at the northern end of terpret our findings in the context of the more the archipelago, averaging 1300 to 1550 mm per general picture of Pleistocene biogeography and annum on Grand Bahama and Great Abaco, paleoecology that has emerged from our recent respectively. On the islands of the Great Bahama studies in the Antilles. Yet this does not alter the Bank, rainfall ranges from 1295 mm per annum fact that the fossil vertebrates of the Bahamas are on New Providence, in the north, to 920 mm per annum on Long Island, in the south. The south¬ Storr L sO. lson D, epartmen ot Vfertebrat eZoolog yN, ationa Ml useum ern islands are quite dry (860 mm per annum on of Natura lHistory ,Smithsonian Institution ,Washington ,D .C. 20560. Gregory K. Pregill, Natural History Museum, P.0. Box Mayaguana; 738 per annum on Great Inagua) 1390 ,San Diego ,California 92112. and vegetation here consists mainly of xeric 1 2 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY Figure 1.—Map of the Bahamas showing the extent of the present banks and thus the approximate configuration of the islands during the last glaciation. NUMBER 48 3 lands, showing that in Wisconsinan times, the frogs” were also included in this sample (G. M. West Indies as a whole were more arid, and open Allen, 1937:370), but these were never studied savanna and scrubland habitats were much more and they cannot now be located in the MCZ prevalent than today (Pregill and Olson, 1981). collections (Ernest Williams, pers. comm.). This Although the Bahamas are riddled with sink¬ may have been the “mass of small miscellaneous holes and caves, such as usually provide ideal sites bones” from which Williams forwarded speci¬ for the accumulation of fossil vertebrates, the mens to Koopman (1951), who identified two islands have been relatively little explored paleon¬ mandibles of bats, one of which belonged to a tologically. Barbour (in Lawrence, 1934) and species ( Mormoops blainvillu) that no longer occurs Hecht (1955) lamented that many deposits of in the Bahamas. cave earth have been obliterated for use as fertil¬ Very little was originally recorded about the izer, but there must still be many unexploited Exuma site other than that fossils “were sorted sources of fossils awaiting discovery on the various out by Mrs. Vivienne Knowles from cave earth islands of the Bahamas. excavated for use as fertilizer . . . during the early Among the first fossil or subfossil vertebrates part of 1937” (Wetmore, 1937b;427). Although collected in the Bahamas were those obtained by Wetmore referred to the fossils as having come Froelich Rainey in 1933-34 for Yale University. from Great Exuma, G. Allen (1937) made refer¬ He obtained bones from Great Abaco, Eleuthera, ence only to “Exuma Island.” It was later deter¬ Long, and Crooked islands. The material from mined that these fossils were actually taken on Crooked Island came from one of the Gordon Little Exuma, from a cave known as “Upper Hill caves along the northeast shore, where bones Pasture Cave” located “about fifty feet above sea were obtained from a hard stratum under a layer level facing the western side of Little Exuma” of sand associated with charcoal, food remains, (Hecht, 1955:134). Hecht and party found in and artifacts indicating human occupancy. The 1953 that this and all similar sites in the vicinity specimens were “considered pre-Columbian “had been completely cleared of the fossiliferous though there is no definite criterion to establish cave soils.” The presence of extinct species, such the actual age” (Wetmore, 1938:51). Apart from as the gigantic hawk Titanohierax , combined with introduced mammals, only the rodent Geocapromys the heavy mineralization of the specimens from ingrahami and remains of birds were recorded from the Little Exuma deposits, probably indicates a this site (Lawrence, 1934; Wetmore, 1938). Only Pleistocene age, but as with most Antillean cave Geocapromys was reported from Great Abaco (Im¬ deposits, there is little direct evidence for dating. perial Lighthouse Cave, Hole in the Wall), Hecht and Koopman’s expedition to the Exu- Eleuthera, and Long Island (no precise localities mas in 1953 resulted in the collection of a few given). Although Lawrence’s (1934) account im¬ additional fossils (Hecht, 1955; Koopman et al., plies that these specimens were all derived from 1957). Remains of Geocapromys ingrahami were re¬ archeological deposits, Barbour’s comments (in ported from “a small cave on the west side of Lawrence, 1934) imply that Rainey may have Pigeon Cay just off Mosstown, Great Exuma” been sampling genuine fossil deposits as well. and in “Robertson cave near Williamstown, Lit¬ Shortly after Rainey’s discoveries, vertebrate tle Exuma” (Hecht, 1955:134-135). Koopman et fossils were forwarded to the Museum of Com¬ al. (1957) reported five bones of four species of parative Zoology at Harvard University, suppos¬ bats from a cave near Forest Settlement, Great edly from Great Exuma. Glover Allen (1937) Exuma, and a mandible of an additional species discussed the remains of Geocapromys from this from the cave near Williamstown, Little Exuma. collection and Wetmore (1937b) identified the For the sake of completeness, we shall mention birds, among which were three species of raptors two other papers that are of minimal paleonto¬ that he described as new. Bones of “reptiles, and logical interest. The first of these is a study of 4 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY NUMBER 48 5 species of xerophilic vertebrates, has been tenta¬ known in the Bahamas, the endemic rodent Geo- tively radiocarbon dated at about 18,000 to capromys ingrahami J. A. Allen (1891). The genus 20,000 years before present (Pregill, 1981), which Geocapromys is otherwise known only from the is at or just before the maximum extent of the Cayman Islands (Patton, 1966; Morgan, 1977), Wisconsinan glaciation. While the fossil avifauna Jamaica, Little Swan Island, and Cuba, whence from Banana Hole indicates a more open, arid the ancestors of G. ingrahami doubtlessly origi¬ environment than at present, the herpetofauna nated. The nominate subspecies, G. i. ingrahami , su gg ests that extinction of the more xerophilous is known only from tiny, arid East Plana Cay elements may already have taken place (p. 20), (near Acklins Island but not on the Crooked- thus implying that the deposits formed after the Acklins Bank), where it survives today and is Wisconsinan glacial maximum but before the relatively abundant (Clough, 1972). close of the Pleistocene. On the basis of midden material from Crooked By comparison with the reptiles and birds, the Island, Lawrence (1934) named a new subspecies, mammalian fauna of the Bahamas is quite de¬ Geocapromys ingrahami irrectus, to which she referred pauperate. Because we do not otherwise deal with specimens from Eleuthera and Long islands, al¬ the fossil mammals, we shall use this opportunity though as we have mentioned, it is not certain to evaluate the status of the few taxa thus far whether these came from midden or fossil depos¬ known. its. G. M. Allen (1937) and Koopman et al. (1957) Raccoons ( Procyon lotor elucus ) are known to referred fossil specimens from Great and Little have been introduced to Grand Bahama from Exuma to G. i. irrectus. Remains far in excess of Florida around 1932 or 1933 (Sherman, 1954), 500 individuals of Geocapromys were collected from but a population found on New Providence was Banana Hole on New Providence, and Morgan described from a single specimen as an endemic (1977) mentions specimens at Florida State Mu¬ species, Procyon maynardi Bangs (1898). In his re¬ seum from Andros and Cat islands. Presumably vision of Procyon , Goldman (1950) retained P. these would be referable to the same taxon as the maynardi as a full species on the basis of three specimens from other islands on the Great Ba¬ specimens, but noted that it was most similar to hama Bank. The specimens of G. ingrahami re¬ Procyon lotor incautus of the extreme southern Flor¬ ported by Wing (1969) from midden deposits on ida keys. With seven additional specimens, Koop- San Salvador were not identified to subspecies man et al. (1957:164) found that the cranial and and were subsequently lost (G. S. Morgan, pers. dental characters alleged by Goldman did not comm.). San Salvador was never part of a larger hold and they considered '‘‘‘maynardi as at best no island and was isolated from the island formed more than a subspecies of P. lotor.” Presumably by the Great Bahama Bank during the Wiscon¬ the only distinction that can now be ascribed to sinan glaciation. Furthermore, Crooked Island, maynardi is Goldman’s assertion that it is darker the type-locality of G. i. irrectus , is likewise part of than incautus. The fact that P. 1. maynardi occurs a separate island system—the Crooked-Acklins only on the most densely populated island in the Bank. A few specimens from Great Abaco, on the Bahamas but nowhere else on the Great Bahama Little Bahama Bank, were designated by Law¬ Bank, and the fact that there are no fossils of rence (1934) as a third subspecies, Geocapromys Procyon in the rich material from Banana Hole, ingrahami abaconis , but again it is not certain makes it very unlikely that Procyon can be re¬ whether these were derived from midden or fossil garded as occurring naturally in the Bahamas. deposits. The extent to which Amerindians trans¬ Until there is evidence to the contrary, we shall ported Geocapromys from one island to another is regard it as having been introduced. not known, so that in the absence of series of Thus, discounting Procyon and excepting bats, genuine fossils from each bank system, it would there is only one species of native land mammal be difficult to evaluate the taxonomic status and 6 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY natural distribution of the various populations of the subspecific level within the Bahamas is prob¬ G. ingrahami, even if consistent morphological dif¬ ably an indication of the relative recency of its ferences could be demonstrated between popula¬ arrival, but there is no apparent reason why it tions on different banks. should have arrived alone. What caused G. ingrahami to become extinct A review of the extant and fossil bats of the everywhere in the Bahamas except on East Plana Bahamas provides more useful information than Cay? To what extent was it affected by the late the non-chiropterans. The fossil bats from Ba¬ Pleistocene changes in habitats that caused the nana Hole, New Providence, have not yet been extinction of many other vertebrates in the Ba¬ studied in detail, but Karl Koopman, to whom hamas, and to what extent was it affected by we continue to be indebted, has identified speci¬ human predation and human-wrought environ¬ mens representing three significant range exten¬ mental changes? Again, the possibility of Amer¬ sions among this material. indian transport obfuscates our knowledge of Disregarding two living species that are known events in the history of Geocapromys , because only from single accidental or mislabeled speci¬ Amerindians could have carried the animals to mens, eleven species of bats are extant in the islands where they had become extinct naturally. Bahamas (Koopman et al., 1957; Buden, 1975, The fact that remains of Geocapromys occur in 1977; Baker and Genoways, 1978). Four of these, middens on a particular island does not necessar¬ Monophyllus redmani , Artibeus jamaicensis, Lasiurus ily mean that the rodents occurred there naturally borealis , and Tadarida brasiliensis , have not been at the same time or were even liberated there, as reported as fossils in the Bahamas. Macrotus water- they could well have been raised in captivity. For housu, Erophylla sezekorm , Eptesicus fuscus, Natalus example, the rodent Isolobodon portoricensis is lepidus , and N. tumidifrons are known from fossils known as a fossil only from Hispaniola. Although from the Exumas (Koopman et ah, 1957). Of it is abundant in middens on Puerto Rico, whence these, only N. tumidifrons does not occur in the originally described, it does not occur there as a Exumas today. fossil, nor in any noncultural context (Olson, pers. Two species of bats are known from the Baha¬ observ.). Furthermore, the same species, along mas only as fossils. Mormoops blainvillii, endemic to with the flightless rail Nesotrochis debooyi , which is the Greater Antilles, was found in the Fittle known from fossils in Puerto Rico, is found in Exuma deposits (Koopman, 1951) and in Banana middens in the Virgin Islands, including St. Croix Hole, New Providence (Koopman, pers. comm.). (Olson, 1974). Because St. Croix is not part of the Pteronotus parnelli, which occurs in the Greater Puerto Rican Bank, it is unlikely that it would Antilles and much of Central and South America, have had the same species of flightless rail as but has not hitherto been recorded from the found on Puerto Rico. Thus N. debooyi must have Bahamas, was also found in the Banana Hole been brought there by Amerindians. Not only did deposits (Koopman, pers. comm.). Amerindians clearly transport native animals Monophyllus redmani and Brachyphylla cavernarum from place to place in the West Indies, but they have only recently been taken in the Bahamas, also appear to have practiced some form of ani¬ and then only on islands south of the Crooked mal husbandry as well. Island Passage (Buden, 1975, 1977). B. cavernarum , Why is there only a single native species of however, was found as a fossil in Banana Hole terrestrial mammal in the Bahamas? In Cuba, (Koopman, pers. comm.), suggesting that this the most likely source of colonizers, there were species, and perhaps Monophyllus redmani as well, several different genera and species of insectivores was once more widely distributed in the Bahamas and edentates, as well as a considerable radiation and subsequently withdrew to the south. of capromyid rodents (Varona, 1974). The fact Natalus tumidifrons is endemic to the Bahamas, that Geocapromys has differentiated at best only at where it is known only from San Salvador and NUMBER 48 7 Great Abaco. It is absent from the islands of the We doubt that competitive replacement by the Great Bahama Bank, where, however, it was smaller species N. lepidus , as suggested by Koop- found as a fossil on Great Exuma. Similarly, the man et al. (1957), is a likely explanation. No such present Bahaman distribution of the West Indian competitor exists for the woodpecker, yet its pat¬ Red-bellied Woodpecker, Melanerpes superciliaris, tern of distribution is virtually the same as that includes only San Salvador, Great Abaco, and of N. tumidifrons. also Grand Bahama (where, however, it may now Although the published fossil record of bats in be extinct). It, too, is absent from islands of the the Bahamas is scant, there is evidence of the Great Bahama Bank, but fossils of it are known same patterns of extinction and fragmentation of from Little Exuma and New Providence. Its range that are so strongly manifested among the patchy distribution appears to have been caused birds (p. 54), and also of contractions in range by environmental changes (p. 45), and it is prob¬ southward, as has apparently occurred with rep¬ able that the same is true of Natalus tumidifrons. tiles (p. 20) and to a lesser extent with birds. Olson, Storrs L. and Pregill, Gregory K. 1982. "Introduction to the Paleontology of Bahaman Vertebrates." Fossil vertebrates from the Bahamas 48, 1–7. View This Item Online: https://www.biodiversitylibrary.org/item/266616 Permalink: https://www.biodiversitylibrary.org/partpdf/352108 Holding Institution Smithsonian Libraries Sponsored by Smithsonian Institution Copyright & Reuse Copyright Status: In copyright. 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